The invention relates to a long forging machine for the forging of round or sharp-edged bar, with four drive units radially arranged on a plane transverse to the forging axis, with synchronously driven rams which carry pairs of oppositely positioned tools, the rams being guided in straight guides by steering levers which may be selectively retained in place with respect to the machine frame or swivelled on the vertical plane together with the rams which are in their retained positions relative to the straight guides. The drive units are known both in the form of a synchronized mechanical drive and a hydraulic drive with working cylinders.
To clearly describe the background of the invention, the long forging machines generally in use will now be described:
Two types of long forging machines are strictly radial forging machines with linearly and radially guided rams or tools. Since the tools are driven synchronously on a common vertical plane, the tool width is determinant for the end position of the stroke at which the tools will collide. However, the width of the tool cannot be selected optionally small in order to permit a workpiece to be forged down to the smallest section in a single process due to the fact that a relatively small tool width would limit the reduction per forging stroke. Since the forging technique calls for a heavy reduction at the very beginning of a forging process, the tool is generally sized to permit the workpiece to be heavily reduced by turning and preforging the work piece round, down to a cross sectional size at which the tools collide. Consequently, one of the known machine types requires the tools to be changed to produce the final forging section The other type, a strictly radial forging machine, permits the tools to be shifted equidirectionally and transverse to the forging axis, i.e. the smaller one final section, the larger the amount of shift. A tool change requires time, whereas shifting movement of the tools by motor requires an elaborate mechanism "THE RUMX Radial Forging Machine" by M. G. Green and F. P. Ecken, SMS Sutton, Inc., SMS Hasenclever Div., Pittsburgh, Pa.;
The invention is based on a third type of long forging machine described in German Patent DE-PS 21 59 461, corresponding to U.S. Pat. No. 3,837,209, on the understanding that, due to the possibility of guiding the tools in a curve alternatively to the radial movement this type of machine can preforge the workpiece in a sort of "forging rolling process" which ensures optimum forging of the center of the workpiece at the heaviest reduction possible. Owing to the selective mode of moving the tools either linearly or in a curve relative to the centerline, this forging machine can produce sharp-edged workpieces with square or rectangular sections as well as round bars. To forge round bars, the rams carrying the tools are fixedly positioned relative to the straight guides by steering levers which cause the tools to perform a uniform and equidirectional swivel movement on a vertical plane, thereby effecting a "forging rolling movement". As a result of the swivel motion of the tools in the manner of an iris diaphragm, the forging machine requires only one set of tools for its entire working range (FIGS. 1 and 2). To forge square or rectangular sections strictly by the radial method with fixedly positioned steering levers, the tools of this type of forging machine must also be changed or shifted transversely to the forging axis for small final sections.